# Methodology

> How Water Treatment Pro researches equipment, prices and water problems, including sourcing, cost models and limits.

Canonical: https://watertreatmentpro.com/methodology/

Last updated: 2026-11-08

Every number on this site is either sourced or labelled as an estimate. This
    page explains the difference, and how a claim gets from a spec sheet to a
    published page.

## 1. Primary sources first

    For equipment we work from the manufacturer's spec sheet and the NSF/ANSI
    certification listing for the specific model — 42 for taste and odour, 44 for
    softeners, 53 for health contaminants, 58 for reverse osmosis. For prices we
    use published retail and installed-price ranges, and for water problems we
    use state health department and EPA guidance on private wells.

## 2. Cost models show their inputs

    Installed cost is modelled from visible inputs: equipment price, installation
    scope (drain, electrical, permit, bypass), consumables per year, and a
    five-year service reserve. We do not present a single "average cost" as if it
    were a quote; the range and what it includes are stated on the page.

## 3. Product selection

    We compare certified removal, capacity against household use, five-year cost
    per gallon, parts availability and warranty. A product earns a recommendation
    when it meets the stated criteria; it cannot buy a place in a ranking. Every
    affiliate relationship is disclosed on the page and in the footer.

## 4. What we have not tested

    We do not run a laboratory and we do not install every system we write about.
    When a claim comes from a manufacturer spec, a certification listing or an
    installer report, we say which. We do not imply first-hand testing we did not
    perform.

## 5. Sources we work from

     |
       | Source type | What it decides | How it is cited

       | NSF/ANSI listings | Which contaminants a unit is certified to remove | Standard number and model named

       | Manufacturer spec sheets | Grain capacity, flow rate, membrane output | Spec reproduced with the model

       | Municipal water quality reports | Baseline hardness, chlorine, nitrate | Supplier and year named

       | State well guidance | Testing intervals and contaminant limits | State agency named

       | Published parts and salt pricing | Running cost per year | Price band with the month checked

    When two sources disagree, the page says which one it followed and why. A
    figure that cannot be traced to a document is labelled an estimate, and an
    estimate is never presented as the price of a specific install.

## 6. Listings and directory data

    The service-area directory is compiled from public business records: the
    firm's own website, its published address and phone number, and the state or
    local licence register named on the city page. A record is marked verified only
    when the name, address, phone and licence have been checked against those
    sources and the date of the check recorded; everything else is labelled. Where
    a source does not publish a ZIP code or a website, the field is left blank
    rather than guessed.

## 7. Corrections

    If a certification changes or a reader finds an error, we update the article
    and its "last updated" date. Email
    [contact@watertreatmentpro.com](mailto:contact@watertreatmentpro.com)
    with the page and the correction.